Internal drag roller



W. R. 1159M 19,09

I INTERNAL DRAG ROLLER Filed May 25, 1.955 2 Sheets-Sheet 1 INVENTOR.

/1 TTORNEY "Jan; 75,1958 W. R. ISOM 29,819, 9

INTERNAL DRAG ROLLER Filed May 25, 1953 2 Sheets-Sheet 2 INVENTOR;

D IZI/ JI 1?. [10/]? ATTORNEY United States Patent INTERNAL DRAG ROLLERWarren R. Isom, West Collingswood, N. J., assignor to Radio Corporationof America, a corporation of Delaware Application May 25, 1953, SerialNo. 356,940

Claims. (Cl. 271-25) This invention relates to film advancing apparatus,and particularly to a damping unit used in obtaining a constant anduniform film speed at a sound translation point.

Film drive systems for sound recording and reproduction, wherein a drivesprocket is used for advancing perforated film, are well-known. Thesesystems generally have a film-pulled drum with a flywheel on its shaftand .a tensioned filter in the loop between the sprocket and drum. Insuch systems, it has been found desirable to introduce friction or adrag at some point in the mechanism. For instance, felt friction pads onthe sound drum ball bearings have been used, as well as friction applieddirectly to the flywheel on the drum shaft. Further more, variousfrictional devices have been applied to the pressure roller. However, inall these instances, this type of frictional application does notcompletely solve the problem.

Other forms of damping have been in the form of eddy current brakes onthe flywheel or a viscous drag on the flywheel by running it in oil orWater. It was found that viscous resistance gave better results, becauseit contributed to the damping of the system. Adding a resistance of anynature to the flywheel or sound drum had two important bad effects. Onewas to limit the effectiveness of the flywheel, and the other was tocause slippage of the film on the sound drum. These two effects limitedthe usefulness of this method of applying damping, even though it provedthat viscous friction was preferred over mechanical friction.

The present invention avoids these two bad effects by applying a viscousfriction to the pressure roller which holds the film on the sound drum.By the use of silicon oil, which is not subject to viscosity changeswith temperature within the range of temperatures to which it issubjected, and placing this oil within the pressure roller, not only theamount of drag obtained can be controlled by varying the viscosity ofthe silicon, but also this drag may be controlled by the amount ofclearance or space provided within the roller for holding the siliconoil. The application of viscous friction by the pressure roller causesno slippage between the drum and the film. Also, because the resistanceor drag is at the pressure roller, the additional tension in the filmmore tightly binds the film to the sound drum, and thereby makes theflywheel more effective as a film stabilizing factor.

Furthermore, since there is suflicient tension in the film loop betweenthe sprocket and sound drum, the resilient filter in the loop can bedamped so as to eflectively minimize oscillation in the over-all system.The invention is particularly adaptable for introducing viscous frictionin a loose loop film path of film recorders and reproducers at thepressure roller so that the advantages of a tight loop system can beincorporated in a loose loop system and still preserve all of theinherent advantages of the loose loop system.

The principal object of the invention, therefore, is to facilitate theconstant and uniform advancement of film.

2,81%,fifiti Patented Jan. 7, 1958 ice Another object of the inventionis to provide an improved constant and uniform film advancing drivemechanism.

A further object of the invention is to provide an im-' proved dampingelement for a constant speed film advancing mechanism.

Although the novel features which are believed to be characteristic ofthis invention will be pointed out with particularity in the appendedclaims, the manner of its organization and the mode of its operationwill be better understood by referring to the following description,read in conjunction with the accompanying drawings, forming a parthereof, in which:

Fig. 1 is an elevational view of a film drive mechanism embodying theinvention.

Fig. 2 is a cross-sectional view of one modification of a dampingpressure roller used in the system of Fig. l, and

Fig. 3 is a cross-sectional view of another modification of the dampingpressure roller shown in Fig. 2.

Referring now to Fig. 1, a film drive system is mounted on a mountingplate 5, which may be part of a picture projector. A film 6 may comefrom a supply reel or from the intermittent advancing mechanism of apicture projector. It passes in a loop over guide roller 7, over astabilizing drum 8, which has a flywheel on its shaft, then into an 8loop around filter rollers 10, over a film advancing sprocket 11 withits shoe 12, and then to a holdback sprocket 14 with its shoe 15. Aportion of an optical sound reproducing assembly is shown at 17. Theshoes and other elements are mounted on the plate 5 in the usual manner,such as by screws 9 and 13.

The jockey or filter roller unit 18 having rollers 10 is of the typedisclosed in Bartelson U. S. Patent No. 2,685,417 of August 3, 1954. Inbrief, this unit comprises the rollers 10 mounted on the diametricallyopposite ends of a sector-like plate 20 fixed to a rotatable shaft 21 onthe other end of which is wound a spring encased in a housing filledwith oil, preferably silicon. The movable plate 29 has an arcuate,elongated slot 22 therein for reception of a fixed pin 23, the slot andpin acting as a limiter for the movement of the rollers 10.

The film 6 is in a tight loop between the sprocket 1i. and the drum 8,and the tightness is controlled by the adjustment of the tension appliedto the filter rollers 10. The film is in a loose loop as it approachesroller 7 and contacts the drum 8. Mounted adjacent the drum 8 andapplying pressure to the film thereon in any suitable manner, such as bya spring, is a pressure roller 25 having a rubber or neoprene tire 26thereon (see Fig. 2). The rollershown in Fig. 2 has a sleeve bearing,while the roller shown in Fig. 3 has roller bearings.

Referring now to Fig. 2, the roller is formed of an inner cylindricalmember 28 mounted on an arm 29 by a screw 30. The member 28 has radialholes or openings 32 and an annular recess 33 in the outer centralportion of its cylindrical wall. Mounted for rotation on the member 28,is a cylindrical bearing member 35, on one end of which is a guideflange 36 having a recessed cylindrical portion for supporting the tire26. The remaining element of the roller is an outer flange 40, which hasa lip 42 fitted into the member 35 so that centering will be maintained.The flange 4t is attached by screws 41 to the cylinder 35. Before flange40 is assembled, the central portion of the roller is filled withsilicon oil 44. The oil in this reservoir passes through the openings 32to the outer recess 33, where it exerts a viscous drag on the rotatingelements of the roller, and thus provides the improved viscous frictionmentioned above.

Referring now to Fig. 3, this roller construction has a centralcylindrical member 50 attached to an arm 51 by a screw 52. -At theends-fof a narrowef'diameter section of the member 50 are mounted ball.bearings 57 and .58, which are properly located axially by spacer 73 andsecured by screw 75. A rotatable cylinder 61 is mounted onthe bearings,on the-right-hand .end of Which .is a guide flange 62. Thecentralportion of the cylinder- 61 is recessed to accommodate a tire 63, whichmaybe of neoprene orrubber similar to the tirei26 shown in Fig; 2.

"This rollerin Fig; 3 has an-outerlflange 65 with. a lip 66, which isfitted into the cylinder for centering and for making secure the ball.bearings 57 and 58, the flange being attached to cylinder=61 by screws67. Similarly to the roller shown in Fig. 2,. silicon oil 69 isplaeedat" the center of the roller before thefl-ange 65ais assem bled. Thisoil passes: through. openings 77nand 79 ,and time the clearance 71betweenythetspacer 73 and-the cylinder 61. The oil, which is also inthenbearingsy57-and 58, introduces to the rotatinglportions-of theroller-a Niseous resistance which has been found to.providei-thetsnecessary drag discussed above, thereby-prov-i-dingaloose-sloop constant speed film drive systern withthe advantagesof atight loop system.

. A feature ofithe above .constru ctionis'the mannerin which the siliconoilis heldwvithin'the rollers. T-he fit at 81 between the member 28=andflange -36-permi-ts -free running of theflange, but close-enough soithatthe clearance is bridged by theoiliwhich is held in place by surfacetension. This provides. a.staticcapillaryseabwhen the roller is at rest,:the fiuid-eventually flowing or draining .back into the reservoir. Whenthe roller is running, the, diiferencein velocity between theinsidesurface-of the cylinder 35. and the outer .surface of: cylinderfZSas at point. 85, reduces .the pressure. 1 at the point 181 as the flowof oil is fromthe center .ofuthe roller to the outside thereof.Thisproduces as'dynamic velocityseal against leakage when the roller :isoperating.

Theseztypes' of sealing actions are-also presentin the roller bearingroller ofFig: 3. wln this construction, the difierence in velocity isproduced. by the difference between the diameter of the small shouldenofmember 50 and the diameter of the inner racesof the ball bearings 57 and58. i

I claim:

1. In a film'drive system having a drive sprocket for pulling film overan inertia drum, a drive sprocket,-an inertia drum, a tensioning meansbetween said sprocket and drum, said film being adapted to:approachsaid'drum in a loose loop and pass over saidtensioning means tosaid sprocket in a tight loop, a pressure roller, means for supportingsaid roller for-movement into and-out-of contact with said drum, saidroller being adapted to contact film passing over saididrum, and meanswithin said roller for applying a uniform internal viscous drag to thesurface of said roller and a resistance :to'the passage of film oversaid drum, said viscous drag means including a fixed inner cylinder and,anouten'cylinder rotata'blewith respect to said innercylinder.

2. A film drive system inaccordance with claim 1 in which saidtensioningmeans between said sprocketand said drum forms an S path for filmadapted to pass between said sprocket and drum.

3. A film drive system'in accordance with; claim 1. in

4 which silicon oil is provided between said cylinders'to provide saidviscous drag.

4. A viscously damped roller comprising a fixed hollow cylindricalmember, a second cylindrical hollow member surrounding and rotatablewith respect to said fixed cylindrical member, oil within said fixedmember, a space be ing provided between said fixed member and saidrotatable member, said fixed member having centrally located openingsthereinto .permitsaid oil tofiowstherethrough into said space., and acl'osurernember for one end of said rotatable member for holding said.oil insaidlfixedmember and centering said rotatable member 'thereon.

5. A viscously damped roller in accordance with claim 4 in whichsaidrotatablamember:has.a guide ilange at one end thereof, saidclosure-memberforrning a guide flange at the other end of said rotatablemember, and an antislip tire around the central portion thereof.

6. A viscously damped roller in accordance with claim 5 in which saidoil is silicon.

-7. A damping roller comprising. a central fixed cylindrical member,ball bearings mountedon and adjacent the ends ofsaid member, a rotatablemember mounted on said ball bearings, oil within the central portion ofsaid fixed member, and openings-in said first mentioned member forpass'ingoil within saidmember to said ball bearings.

8. A damping roller in accordance with claim 7,in which guide flangesare 'mounted at the ends of said rotatable member and an anti-slip tireis over the central portion of said rotatable member.

9. A damping roller iiraccordancewith claim 7, in which said oil issilicon.

10. A viscously damped roller comprising a fixed hollow cylindrical.member havinga cylindrical wall and one end open, asecond hollowcylindrical member surrounding and rotatable-With respect to :said fixedcylindrical member and having one end open, oil Within said fixedmember, said fixed member having an annular recess in the outer centralportion of its cylindrical wall and openings therein passing throughsaid cylindrical wall fromthe interior of said fixed member to saidrecess, and a closure member for the open ends of' said cylindricalmembers for holding said oil in said fixed member and centering saidrotatable member thereon.

.References Cited in the file of this patent UNITED STATES PATENTS1,998,931 Kellogg, Apr..- 23, .1935 2,099,376 ,Shapiro Nov. 16,19372,112,894 Hasbrouck Apr. 5, 1938 2,157,393 Black May 9, 1939 2,206,380Zimmerman July 2, 1940 2,417,282 Wheeler ,a-Mar. 11, 1947 2,499,210-Bartelson Feb. 28, 1950 2,586,600 B.artelson Feb. 19, 1952 2,618,370Orwin. Nova 18, 1952 2,622,707 Faus Dec. 23, 1952 2,685,417 BartelsonAug. 3, 1954 FOREIGN PATENTS 136,834 Australia Mar. 17, 1950 414,642Great Britain Aug. 7, 1934

